Method and device for estimating signal power in compressed audio using scale factors

• US 7,356,464 B2
• Filed: 05/08/2002
• Issued: 04/08/2008
• Est. Priority Date: 05/11/2001
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Barbieri, Mauro, Snijder, Freddy, Nesvadba, Jan Alexis Daniel, Stella, Alessio
• Primary Examiner(s): Edouard; Patrick N.
• Assistant Examiner(s): Stoffregen; Joel
• Application Number:
  US10/476,965
• Publication Number:
  US 20040138880A1
• Time in Patent Office: 2,162 Days
• Field of Search: 704/210, 704/215, 704/233, 704/200.1, 381/56
• US Class Current: 704/210
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: H04H 60/58 of audio determination or detection of speech characteristics in general G10L25/00; speech recognition in general G10L15/00
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4394 involving operations for analysing the audio stream, e.g. detecting features or characteristics in audio streams arrangements characterised by components specially adapted for monitoring, identification or recognition of audio in broadcast systems H04H60/58
• CPC Class Codes: H04N 21/812 involving advertisement data advertising per se G06Q30/02
• CPC Class Codes: H04N 5/602 for digital sound signals

Abstract

Estimating a signal power in a compressed audio signal [A] is provided, the audio signal comprising blocks of quantized samples, a given block being provided with a set of scale factors. The estimating is performed by extracting the set of scale factors from the compressed audio signal, and estimating the signal power in the given block based on a combination of the scale factors. Advantageously, the extracting step and estimating step are performed on only a sub-set of the set of scale factors. The signal power estimation may be used in a silence detector (11) for use in a receiver (1).

Claims

1. A method of estimating a signal power in a compressed audio signal, the compressed audio signal comprising a plurality of narrow sub-band signals, each narrow sub-band signal comprising frames of quantized samples, each frame further being divided into a plurality of sub-blocks of quantized samples, each sub-block of each frame of each sub-band being provided with a corresponding scale factor, the method comprising:

extracting a sub-set of the set of scale factors from the compressed audio signal, and

estimating the signal power in a given frame based on a combination of the sub-set of the scale factors,

wherein the sub-set of the scale factors includes only the maximum scale factor in each sub-band in the given frame.

2. A method as claimed in claim 1, wherein the sub-set mainly includes the scale factors of a number of lower frequency sub-band signals.

3. A method as claimed in claim 1, wherein the compressed audio signal is a stereo or multi-channel signal, wherein the extracting step is performed on only a subset of the available channels.

4. The method of claim 1, wherein estimating the signal power in a given frame based on a combination of the sub-set of the scale factors includes:

squaring each scale factor in the sub-set of scale factors; and

adding the squared scale factors to produce the estimate of the signal power in the given frame.

5. A device for estimating a signal power in a compressed audio signal, the compressed audio signal comprising a plurality of narrow sub-band signals, each narrow band signal comprising frames of quantized samples, each frame further being divided into a plurality of sub-blocks of quantized samples, each sub-block being provided with a corresponding scale factor, the device comprising:

means for extracting a sub-set of scale factors from the compressed audio signal, and

means for estimating the signal power in a given frame based on a combination of the sub-set of the scale factors,

wherein the sub-set of the scale factors includes only the maximum scale factor in each sub-band in the given frame.

6. The device of claim 5, wherein the means for extracting the sub-set of the scale factors mainly extracts the scale factors of a number of lower frequency sub-band signals.

7. The device of claim 5, wherein the compressed audio signal is a stereo or multi-channel signal, and wherein the means for extracting the sub-set of the scale factors extracts the scale factors of only a subset of the channels.

8. The device of claim 5, wherein the means for estimating the signal power in a given frame based on a combination of the sub-set of the scale factors is adapted to square each scale factor in the sub-set of scale factors, and to add the squared scale factors to produce the estimate of the signal power in the given frame.

9. A silence detector comprising:

a device as claimed in claim 5 for obtaining an estimate of the signal power of a compressed audio signal, and

means for evaluating the estimate of the signal power in order to detect silences in the audio signal.

10. A receiver for receiving a compressed audio signal, the receiver comprising:

an input for obtaining a compressed audio signal,

a silence detector as claimed in claim 9 for detecting silences in the compressed audio signal, and

means for influencing the audio signal wherein the influencing at least partly depends on the detection of the silences.